Self-repairing, reinforced matrix materials

Abstract

Self-repairing, fiber reinforced matrix materials include a matrix material including inorganic as well as organic matrices. Disposed within the matrix are hollow fibers having a selectively releasable modifying agent contained therein. The hollow fibers may be inorganic or organic and of any desired length, wall thickness or cross-sectional configuration. The modifying agent is selected from materials capable of beneficially modifying the matrix fiber composite after curing. The modifying agents are selectively released into the surrounding matrix in use in response to a predetermined stimulus be it internal or externally applied. The hollow fibers may be closed off or even coated to provide a way to keep the modifying agent in the fibers until the appropriate time for selective release occurs. Self-repair, smart fiber matrix composite materials capable of repairing microcracks, releasing corrosion inhibitors or permeability modifiers are described as preferred embodiments in concrete and polymer based shaped articles.

1 . A structure comprising: 
 a matrix comprising an interconnected continuous structure of a plurality of hollow fibers having a length of less than about  1  inch, the fibers comprising modifying agent that is contained until released to flow into the matrix in response to an external stimulus.    
     
     
         2 . The structure of  claim 1  wherein the matrix comprises a three-dimensional shape.  
     
     
         3 . The structure of  claim 1  wherein the external stimulus is heating, cooling, loading, impacting, cracking, water infusion, chloride infusion, alkalinity changes, acidity changes, acoustic excitation, low frequency wave excitations, hydrostatic pressure, rolling pressure, light sensitivity or laser excitation, electric current, voltage, electrorheological excitation, or radiation.  
     
     
         4 . The structure of  claim 1  wherein the hollow fibers comprise fiberglass, cement, asphalt, hydroxyapatite, glass, ceramic, metal, polyolefin, polyester, polycarbonate, polyacrylate, polyarylate, polyamide, polyimide, polyaramide, polyurethane, carbon, graphite, cellulose, nitrocellulose, hydrocarbon, or piezoelectric material.  
     
     
         5 . The structure of  claim 1  wherein the hollow fibers have at least one end open to the outside.  
     
     
         6 . The structure of  claim 1  wherein the hollow fibers have at least one open end.  
     
     
         7 . The structure of  claim 1  wherein the hollow fibers comprise a coating which will selectively degrade upon the occurrence of a particular external stimulus.  
     
     
         8 . The structure of  claim 7  wherein the coating is a heat sensitive coating, a pH sensitive coating, or an ion sensitive coating.  
     
     
         9 . The structure of  claim 8  wherein the coating is a wax, low molecular weight hydrocarbon oil, or coating polymer.  
     
     
         10 . The structure of  claim 7  wherein the particular external stimulus is heating, cooling, loading, impacting, cracking, water infusion, chloride infusion, alkalinity changes, acidity changes, acoustic excitation, low frequency wave excitations, hydrostatic pressure, rolling pressure, light sensitivity or laser excitation, electric current, voltage, electrorheological excitation, or radiation.  
     
     
         11 . The structure of  claim 1  wherein the modifying agent of the fiber is a fluid.  
     
     
         12 . The structure of  claim 1  wherein the modifying agent is methyl methacrylate, styrene, or epoxy.  
     
     
         13 . The structure of  claim 1 , wherein the matrix comprises a ceramic, metal, cementitious or polymer matrix.  
     
     
         14 . The structure of  claim 13 , wherein the matrix material comprises metal and the metal is any of aluminum, iron, lead, copper, steel, bronze, phosphor bronze, and brass.  
     
     
         15 . The structure of  claim 13 , wherein the matrix comprises a cementitious material and further comprises a reinforcement.  
     
     
         16 . The structure of  claim 1 , wherein the matrix comprises a biomimetic system.  
     
     
         17 . The structure of  claim 16 , wherein the biomimetic system comprises organic or inorganic materials.  
     
     
         18 . The structure of  claim 1 , wherein the structure is a biomedical device.  
     
     
         19 . The structure of  claim 1 , wherein the structure is an aircraft structure, a space vehicle or a satellite.  
     
     
         20 . The structure of  claim 1 , wherein the structure is a bridge or a building.  
     
     
         21 . The structure of  claim 1 , wherein the structure is a helicopter blade.  
     
     
         22 . The structure of  claim 1 , wherein the structure is a sandwich panel.  
     
     
         23 . A structure comprising: 
 a matrix comprising an interconnected continuous structure of a plurality of porous walled, hollow fibers comprising a repair chemical that is contained until released to flow into the matrix.    
     
     
         24 . The structure of  claim 23  wherein the hollow fibers have a length of less than about 1 inch.  
     
     
         25 . The structure of  claim 24 , wherein the hollow fibers have a diameter of less than 100 microns.  
     
     
         26 . The structure of  claim 23  wherein the repair chemical of the fiber is a fluid.  
     
     
         27 . The structure of  claim 23  wherein the hollow fibers comprise fiberglass, cement, asphalt, hydroxyapatite, glass, ceramic, metal, polyolefin, polyester, polycarbonate, polyacrylate, polyarylate, polyamide, polyimide, polyaramide, polyurethane, carbon, graphite, cellulose, nitrocellulose, hydrocarbon, or piezoelectric material.  
     
     
         28 . The structure of  claim 27 , wherein the hollow fiber comprises metal and are conductive.  
     
     
         29 . A method of repairing a microcrack in a shaped article, the shaped article comprising a matrix, comprising: 
 providing the matrix comprising a plurality of fibers and a repair chemical; and    releasing the repair chemical from the fibers into the matrix upon an external stimulus.    
     
     
         30 . The method of  claim 29 , further comprising rebonding the fibers to the matrix.  
     
     
         31 . The method of  claim 30 , further comprising repairing the fibers themselves.  
     
     
         32 . The method of  claim 29 , wherein the fibers are twisted.  
     
     
         33 . The method of  claim 29 , wherein the repair chemical comprises two part epoxies, wherein an epoxy precursor material is disposed in a first fiber and a cross-linking agent is disposed in an adjacent second fiber.  
     
     
         34 . The method of  claim 29 , wherein the fiber comprises an external coating, and wherein the method comprises selectively degrading the external upon the occurrence of the external stimulus.  
     
     
         35 . The method of  claim 34 , wherein the external coating comprises wax and the external stimulus comprises heat.  
     
     
         36 . A shaped article of composite material comprising a cured matrix, at least one hollow release vessel, and a modifying agent, wherein the modifying agent is capable of beneficially modifying the composite material in response to a predetermined external stimulus.  
     
     
         37 . The article of  claim 36  wherein the modifying agent is selected from the group consisting of polyolefin, polyester, polyamide, polyaramid, polyimide, carbon, graphite, cellulose, nitrocellulose, hydrocarbons, polytetrafluoroethylene, aramids, polypropylene, and elastomers.  
     
     
         38 . A method for making an in situ composite comprising the steps of: 
 selecting a first reactive chemical;    dispensing the first reactive chemical into a mold containing at least one second reactive chemical, composite fibers, and an activator located in fibers.    
     
     
         39 . The method of  claim 38  wherein the first reactive chemical and the at least one second reactive chemical bond the fibers to each other.  
     
     
         40 . The method of  claim 38  wherein the mold contains a modifying chemical comprising a solvent.  
     
     
         41 . The method of  claim 38  wherein the composite is selected from the group consisting of a wrap, a web or a fabric.  
     
     
         42 . The method of  claim 38  wherein the fibers include a coating that acts as a modifying agent.  
     
     
         43 . The method of  claim 38  wherein the fibers comprise a modifying agent.